<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
<style>
  div{
    width: 100px;
    height: 100px;
    border: 10px solid red;
    border-radius: 30px 50px 0px 0px; /* 左上，右上，右下，左下*/

  }
</style>

</head>
<body>
<div>

</div>
</body>
</html>